The objective of this project is to determine and characterize the highest level of genetic regulation which is altered consistently during malignant transformation, and to correlate these results with other characteristics of tumors in order to explain the molecular mechanism of carcinogenesis. RNA/DNA hybridization techniques will be used to determine whether alteration of selective RNA transport isa ubiquitous characteristic of tumors, irrespective of their cause, tissue of origin, or host species, and to determine whether the single-copy genes show the same pattern of altered control as the genes in the repetitive fraction of DNA. These and other techniques will be used to determine the intracelluar site of chemical attack which results in irreversible alteration of RNA transport control, and to eventually define this control mechanism and its regulation in normal cells.